Thermoplastic molding compositions of polycarbonates and ABS polymers (acrylonitrile/butadiene/styrene) have been known for a long time. Thus, U.S. Pat. No. 3,130,177 A describes readily processable molding compositions of polycarbonates and graft polymers of monomer mixtures of acrylonitrile and an aromatic vinyl-hydrocarbon on polybutadiene.
EP 0 372 336 A2 discloses PC/ABS compositions (polycarbonate/acrylonitrile/butadiene/styrene) having a high toughness at low temperatures, which are characterized in that the graft polymers and/or the copolymers are replaced at least in part by graft polymers and/or copolymers in which the grafted-on material and/or the copolymer contains at least 86 wt. % of vinylaromatics.
DE 102 55 825 A1 discloses PC/ABS compositions of improved surface quality comprising a mixture, obtained by coprecipitation, of at least one graft polymer B*.1 prepared by emulsion polymerization and at least one thermoplastic vinyl (co)polymer B*.2 prepared by emulsion polymerization, as well as at least one thermoplastic vinyl (co)polymer C*.2 prepared by solution, bulk or suspension polymerization, wherein, in a preferred embodiment, the vinyl (co)polymers B*.2 and C* differ in the acrylonitrile content by 1 to 15 wt. %, preferably by 2 to 10 wt. %, particularly preferably by 2.5 to 7.5 wt. %.
EP 0 767 215 A1 discloses compositions comprising polycarbonate, a rubber-modified (acrylonitrile-free) styrene resin and, as a phase mediator, a copolymer or a graft copolymer. The copolymers or the graft shells of the graft copolymers in the compositions according to the invention of EP 0 767 215 A1 are distinguished in that, at the molecular level, they have a non-uniform distribution in respect of the ratio of amounts of the monomers on which they are based, which results in different individual solubility parameters. In the case of a styrene/acrylonitrile copolymer (SAN), the solubility parameters stated in EP 0 767 215 A1 correspond, from the calculation basis described, to a weight-average acrylonitrile content of from 2 to about 12.5 wt. % and a difference between the minimum and maximum individual molecular acrylonitrile contents of from 8 to 26 wt. %.
The object on which the invention is based comprises providing molding compositions having an improved processing stability for the production of complex moldings for automobile construction, which are distinguished by a combination of a good low temperature toughness over a wide processing window and good resistance to stress cracking under the action of chemicals. The present invention also provides molding compositions which, in addition to the abovementioned requirements, also meet the requirements of the European automobile industry on materials in automobile interior construction in limiting the emission of volatile organic components.